JOURNAL CLUB

Sabari krishnan

INTRAAORTIC BALLOON SUPPORT FOR MYOCARDIAL

INFARCTION WITH CARDIOGENIC SHOCK

Holger Thiele, Uwe Zeyer, Franz-Josef Neumann, Miroslaw Ferenc, Hans-Georg Olbrich, Jörg

Hausleiter et al

The NEW ENGLAND JOURNAL of MEDICINE october 4,2012 vol.367 no.14

INTRODUCTION

IABP is a mechanical device that increases

myocardial oxygen perfusion while at the same

time increasing cardiac output

Increasing cardiac output increases coronary

blood flow and therefore myocardial oxygen

delivery

Consists of a cylindrical polythene balloon that sits in aorta, approximately 2cm from the left subclavian artery and counter pulsates

Actively deflates in systole, increasing forward blood flow by reducing after load. It actively inflates in diastole, increasing blood flow to the coronary arteries

These actions combine to decrease myocardial oxygen demand and increase myocardial oxygen supply

NEED OF THIS STUDY A meta-analysis that included only cohort studies

suggested that the use of an IABP is associated with a reduction by 11% in the risk of death.

In the recent (IABP-SHOCK) trial, which involved only 45 patients, no significant difference was observed with respect to the (APACHE II) score for severity of illness between patients assigned to IABP and those assigned to a control group that received standard care, although serial brain natriuretic peptide levels were significantly reduced in the balloon-pump group.

The IABP-SHOCK II trial was designed to test the hypothesis that IABP as compared with the best available medical therapy alone, results in a reduction in mortality among patients with acute myocardial infarction complicated by cardiogenic shock for whom early revascularization is planned

Inconclusive evidence might be one explanation for the current use of IABP in only 25 to 40% of patients with cardiogenic shock, despite the recommendations in the guidelines

METHODS TYPE OF STUDY

Randomized, prospective, open-label, multicenter trial,

Randomization

Internet-based program, with stratification according to center.

PERIOD-june16th,2009-march3,2012

ELIGIBLE CRITERIA Acute myocardial infarction (with or without ST segment elevation)

complicated by cardiogenic shock and if early revascularization (by means of PCI or CABG) was planned.

CARDIOGENIC SHOCK

Systolic blood pressure <90 mm hg for more than 30 minutes

Catecholamine's to maintain a systolic pressure >90 mm hg

Signs of pulmonary congestion and

Impaired end- organ perfusion. Altered mental status Cold, Clammy skin and extremities Oliguria with urine output of less than 30 ml per hour Serum lactate level higher than 2.0 mmol per liter

EXCLUSION CRITERIA Resuscitation for more than 30 minutes

Had no intrinsic heart action were in a coma with fixed

dilatation of pupils that was not induced by drugs

Had a mechanical cause of cardiogenic shock (e. g Ventricular

septal defect or papillary muscle rupture)

Had onset of shock more than 12 hours before screening

Older than 90 years of age

Shock as a result of a condition other than acute myocardial

infarction

Had severe concomitant disease associated with a life

expectancy of less than 6 months

Had a massive pulmonary embolism

Severe peripheral arterial disease precluding

insertion of an IABP or aortic regurgitation

greater than grade II in severity

790

600

301 299

OUTCOMES

NO SIGNIFICANT DIFFERENCE BETWEEN TWO GROUPS

DISCUSSION No immediate improvement in blood

pressure or heart rate between two groups.

Although positive effect of IABP on multiorgan

dysfunction at day 2 and 3, as assessed with

the use of the SAPS II, this effect was not

evident at day 4.

No significant effects on CRP level or serum

lactate level, which were assessed as measures

of inflammation and tissue oxygenation.

Studies showed IABP results in a hemodynamic benefit

as a result of afterload reduction and diastolic

augmentation with improvement in coronary perfusion.

However, the effects on cardiac output are modest

and might not be sufficient to reduce mortality.

In a recent, small, randomized trial, there were no

significant differences in cardiac power output, left

ventricular stroke-work index, or systemic

vascular resistance between patients assigned to

IABP and those assigned to a control group.

Use of IABP before coronary revascularization may

make the revascularization procedure safer by

improving left ventricular unloading.

However, in the current trial, there was no mortality

benefit in the subgroup of patients in whom the IABP

was inserted before the start of revascularization, as

compared with those in whom it was inserted after

revascularization.

In another recent randomized trial involving patients

with large anterior infarctions but without cardiogenic

shock, insertion of a balloon pump before PCI, as

compared with control treatment did not reduce the

infarct size.

LIMITATIONS

① Blinding was not possible because of the nature of the intervention..

② Hemodynamic measurements or assess laboratory inflammatory

markers other than blood pressure, heart rate, and c-reactive

protein levels, not done

③ The slightly lower mortality in trial — approximately 40%, as

compared with 42 to 48% in other randomized trials and registries

— might suggest that trial included a higher percentage of patients

with mild or moderately severe cardiogenic shock, a factor that

could preclude generalization of the results to patients with the

most severe forms of cardiogenic shock.

④ The negative overall result, cannot definitively rule out

a type II error;

⑤ No information about longer-term outcomes. To

minimize bias, use of a central randomization system,

and the members of the clinical events committee

were unaware of the group assignments.

CONCLUSION C O N T R O L L E D T R I A L O F I N T RA AO RT I C B A L LO O N P U M P

S U P P O RT I N PAT I E N T S W I T H C A R D I O G E N I C S H O C K

C O M P L I C AT I N G M YO C A R D I A L I N FA RC T I O N F O R W H O M

E A R LY R E VA S C U L A R I Z AT I O N A S C O M PA R E D W I T H

C O N V E N T I O N A L T H E RA PY , DID NOT REDUCE 30 -DAY

MORTAL ITY.

THANK YOU